This invention relates generally to devices for safely descending a rope. This invention is particularly adaptable to assisting a person to escape from a burning building by safely descending a rope. The device is simple in operation, provides safety in case the person is incapacitated and cannot operate the device, and allows several different persons to descend the same rope simultaneously.
The devices taught by the prior art for safely descending a rope are cumbersome, unsafe for an incapacitated person, or do not permit several persons to descend along a rope at one time.
Use of the present invention is superior to devices of the prior art and also to mountain climbing rapelling techniques. In none of the prior art can both an unconcious person descend safely and several persons descend simultaneously along the same rope. The present invention is safe for an unconscious person because it incorporates a spring which applies pressure to the rope at all times. Several persons can descend simultaneously along one rope because the rope goes straight through the device. Devices of the prior art put bends, twists, or kinks in the rope, and mountain rapelling techniques require that the rope loop around the person descending. If a person's descent puts loops, twists, kinks, or bends in the rope, then a weight below the person interferes with his descent. The present invention puts no loop, twist, bend, or kink in the rope, and so a weight on the rope below a person will not interfere with his descent.
U.S. Pat. No. 3,927,734 discloses an emergency descent device which allows a person to control his descent along a rope. The rate of descent of the person is controlled by friction wherein the rope is pinched between the body of the device and a movable lever. However, the device has an open seat which makes it dangerous for an unconscious or otherwise incapacitated person. Also the rope has a bent path which precludes the descent of several persons simultaneously along one rope.
U.S. Pat. No. 3,889,777 discloses a device to be strapped on a person for controlling descent down a cable or rope. However, the device has a complex set of intermeshing teeth which bend the path of the rope. A weight hanging from the rope below the operator would make the device difficult to operate. In contrast, in the present invention, the application of friction to the rope is mechanically simple, and the path of the rope is not bent by application of friction, thereby avoiding both disadvantages of the prior art.